1. Field of the Invention
The present invention relates to a liquid crystal display device in which at least one polarizing plate having a polarizer is disposed at one side and the other side of a liquid crystal cell.
2. Description of the Related Art
A strong dependence of image on a viewing angle has been a significant drawback of liquid crystal display devices, but the application of such devices as space-saving image display devices with low power consumption has still been widening year after year. In particular, in recent years, a high viewing-angle liquid-crystal mode such as a VA mode and an IPS mode has found practical use, and the demand for liquid crystal display devices has been rapidly growing even in the markets requiring a high viewing angle, such as television set market.
Accordingly, a demand has been created for even higher performance of polarizing plates that are employed in liquid crystal display devices.
Among the properties representing the required high performance, the improvement of endurance with respect to temperature and moisture is particularly important for polarizing plates.
Polarizing plates are usually manufactured by causing the adsorption of iodine in a hydrophilic polymer film such as a poly(vinyl alcohol) film, a partially formalized poly(vinyl alcohol) film, and a partially saponified film of ethylene-vinyl acetate copolymer and stretching the film. However, the problem associated with such polarizing plates is that light leak occurs on the circumference of a panel due to changes in the temperature and moisture of the environment. Shrinkage and relaxation of the stretched hydrophilic polymer is the reason for such light leak, and the light leak is known to be greatly affected by the amount of moisture transmitted from the outside through a protective film.
A method has been disclosed by which a polarizing plate is fabricated by pasting a protective film with a low moisture permeability onto a polarizer to resolve the above-described problem (see Japanese Patent Application Laid-Open (JP-A) No. 2005-309394).
However, in a polarizing plate using a protective film with a low moisture permeability, the process of pasting the protective films so as to sandwich the polarizer and then drying the moisture requires time when a poly(vinyl alcohol) polarizer (sometimes referred to hereinbelow as a polarization film) is employed. The resultant problem is that the productivity of polarizing plates using protective films on both surfaces and employing the conventional cellulose acylate films that have high moisture permeability is low and the production cost is thereby increased.